Level up your multiplication skills! Master regrouping (carrying) when products are bigger than 9. Learn the standard algorithm and become a multiplication expert! 🚀💪
Master regrouping in multiplication through hands-on challenges!
Identify when you need to regroup in multiplication!
Click all correct options
Put the multiplication steps in the correct order!
Drag to sort or use ↑↓ buttons to adjust · Correct Order
Use area models to solve problems that need regrouping!
Master the vertical multiplication algorithm with regrouping!
Solve complex multiplication word problems with regrouping!
Deep dive into regrouping techniques and strategies
Regrouping happens when a multiplication product is 10 or more. We write the ones digit in our answer and 'carry' the tens digit to the next column. This is like making groups of 10 - when we have enough ones to make a ten, we regroup them! The carried number MUST be added to the next multiplication.
School Fundraiser
Selling 28 boxes of cookies at $19 per box. 8×9=72 (write 2, carry 7). 8×1=8, plus carried 7=15 (write 15). 2×9=18 (write 8, carry 1). 2×1=1, plus carried 1=2 (write 2). Partial products: 252 + 280 = $532 raised! 🍪
Theater Seating
A theater has 56 rows with 48 seats each. 6×8=48 (write 8, carry 4). 6×4=24+4=28 (write 8, carry 2). 5×8=40 (write 0, carry 4). 5×4=20+4=24 (write 24). Result: 448 + 2,240 = 2,688 total seats! 🎭
Stamp Albums
Collecting 37 pages with 29 stamps per page. 7×9=63 (write 3, carry 6). 7×2=14+6=20 (write 0, carry 2). 3×9=27 (write 7, carry 2). 3×2=6+2=8 (write 8). Sum: 203 + 870 = 1,073 stamps! 📮
Garden Produce
Harvesting from 64 plants, each producing 57 vegetables. 4×7=28 (write 8, carry 2). 4×5=20+2=22 (write 2, carry 2). 6×7=42 (write 2, carry 4). 6×5=30+4=34 (write 34). Total: 228 + 3,420 = 3,648 vegetables! 🥬
Write carried numbers small above the next column - this helps you remember to add them! Use a different color pencil if it helps you track them.
Forgetting to add the carried number in the next multiplication. Always check: did I add what I carried?
Cash registers use this process electronically when calculating totals. It's the foundation of all large calculations!
Circle all the carried numbers in different colors - this visual cue helps you not forget any!
The standard algorithm is the most common multiplication method used worldwide! Write numbers vertically aligned by place value. Multiply by the ones digit first, then the tens digit (remembering to add a zero placeholder). Add the partial products for your final answer. This method works for ANY size numbers!
Sports Card Purchase
Buying 45 packs at $38 per pack. Set up vertically: 45 × 38. Multiply by 8: 45×8=360. Multiply by 30: 45×30=1,350. Add: 360+1,350=$1,710 total! Remember to place a 0 when multiplying by tens! 🏀
Tile Installation
Installing tiles in 67 rooms, 54 tiles per room. Vertical setup: 67 × 54. First: 67×4=268. Then: 67×50=3,350. Sum: 268+3,350=3,618 tiles needed! Don't forget that 0 placeholder! 🏠
Magazine Subscriptions
School sells 83 subscriptions at $26 each. Algorithm: 83 × 26. Calculate: 83×6=498, 83×20=1,660. Total: 498+1,660=$2,158 revenue! The standard way keeps work organized! 📰
Concert Tickets
Selling 92 groups of 35 tickets each. Vertical multiplication: 92 × 35. First row: 92×5=460. Second row: 92×30=2,760. Add rows: 460+2,760=3,220 tickets sold! 🎫
Keep your columns perfectly aligned! Use graph paper if needed. Misaligned numbers cause calculation errors.
Forgetting the zero when multiplying by the tens digit. Always add that placeholder zero in the second row!
This is THE method taught globally and used in business, science, and engineering. Master it!
Race against a calculator - with practice, you can multiply two-digit numbers almost as fast!
The area model visualizes multiplication as finding the area of a rectangle. Even with regrouping, you break the problem into four manageable pieces. Each piece might require regrouping, but they're smaller and easier! This method helps you SEE why multiplication works and makes mental estimation easier.
Carpet Installation
Room is 58 feet by 46 feet. Area model: (50+8)×(40+6). Sections: 50×40=2,000, 50×6=300, 8×40=320, 8×6=48. Total area: 2,000+300+320+48=2,668 square feet of carpet! 🏡
Chocolate Factory
Making 74 batches with 39 chocolates each. Break down: (70+4)×(30+9). Calculate: 70×30=2,100, 70×9=630, 4×30=120, 4×9=36. Sum: 2,100+630+120+36=2,886 chocolates! 🍫
Parking Lot Design
Planning 85 rows of 67 parking spaces. Model: (80+5)×(60+7). Four sections: 80×60=4,800, 80×7=560, 5×60=300, 5×7=35. Total: 4,800+560+300+35=5,695 spaces! 🚗
Orchard Planning
Planting 93 rows of 28 trees each. Area approach: (90+3)×(20+8). Products: 90×20=1,800, 90×8=720, 3×20=60, 3×8=24. Grand total: 1,800+720+60+24=2,604 trees! 🌳
Label each section of your area model! Writing '50×40=2,000' inside each rectangle prevents confusion.
Making calculation errors in the four smaller multiplications. Work carefully through each section!
Architects and designers use area models constantly for space planning and material estimation!
Try estimating the answer by rounding first, then use the area model to get the exact answer!
Some problems require regrouping at EVERY step! Stay calm and organized. Write each carried number clearly, work methodically through each multiplication, and double-check that you've added all carried digits. The more complex the problem, the more important neat, organized work becomes!
Library Book Order
Ordering 88 boxes with 97 books each. Multiple regrouping: 8×7=56 (carry 5), 8×9=72+5=77 (carry 7). Then: 8×7=56 (carry 5), 8×9=72+5=77 (carry 7). Track each carry carefully! Result: 8,536 books! 📚
School Supply Order
Buying 76 packages of 89 items each. Chain of regrouping: 6×9=54 (carry 5), 6×8=48+5=53 (carry 5). 7×9=63 (carry 6), 7×8=56+6=62 (carry 6). Final: 6,764 supplies! ✏️
Sports Jerseys
Ordering 95 jerseys costing $78 each. Several regroups needed: 5×8=40 (carry 4), 5×7=35+4=39 (carry 3). 9×8=72 (carry 7), 9×7=63+7=70 (carry 7). Total: $7,410! 👕
Event Tickets
Selling 86 blocks of 94 tickets. Regrouping cascade: 6×4=24 (carry 2), 6×9=54+2=56 (carry 5). 8×4=32 (carry 3), 8×9=72+3=75 (carry 7). Answer: 8,084 tickets! 🎟️
Use a checklist: 'Did I multiply? Did I add the carried number? Did I write it correctly?' Systematic checking prevents errors!
Losing track of multiple carried numbers. Write them clearly and cross them off as you use them!
Complex calculations in finance, inventory management, and data analysis require careful regrouping tracking!
Try doing a problem twice using different methods (area model AND standard algorithm) to verify your answer!
Estimation becomes even MORE important with regrouping! Round both numbers to the nearest ten before multiplying. This gives you a quick ballpark answer. After your detailed calculation (with all that regrouping!), compare to your estimate. If they're wildly different, recheck your regrouping steps!
Budget Planning
Need 47 items costing $63 each. Estimate: 50×60=3,000. Calculate precisely: 47×63=2,961. Close to estimate - answer is reasonable! Our budget should be around $3,000. 💵
Distance Calculation
Driving 56 miles per day for 78 days. Estimate: 60×80=4,800 miles. Exact: 56×78=4,368 miles. Makes sense! Plan for about 4,500-5,000 miles. 🚗
Cafeteria Planning
Feeding 84 people, each needs 96 ounces of food. Estimate: 80×100=8,000 oz. Precise: 84×96=8,064 oz. Very close! Order about 8,000-8,500 ounces. 🍽️
Supply Inventory
Stocking 69 classrooms with 85 items each. Estimate: 70×90=6,300 items. Calculate: 69×85=5,865 items. Reasonable! Order around 6,000 items. 📦
Always estimate before calculating! Write it down and circle it. This creates an 'answer target' to aim for.
Trusting your calculation without checking against an estimate. Regrouping errors are easy to make!
Scientists and engineers ALWAYS estimate first. It's the professional standard for catching mistakes!
Play 'Price Is Right' - estimate the total, then calculate. See how close your estimate was!
Real-life situations often create multiplication problems that require regrouping! From budgeting to planning to calculating materials needed, these skills are essential. The key is to: 1) Identify what you're multiplying, 2) Choose your method (standard algorithm or area model), 3) Work carefully through regrouping, and 4) Check your answer with estimation!
School Fundraising Campaign
68 students each sell 79 items. Calculate: 68×79. Using standard algorithm with regrouping: 68×9=612, 68×70=4,760. Total: 612+4,760=5,372 items sold! Fundraiser success! 🎯
Community Garden Project
Creating 57 garden plots, each 48 square feet. Area calculation: 57×48. Method: 57×8=456, 57×40=2,280. Sum: 456+2,280=2,736 square feet of garden space! 🌱
Athletic Equipment Order
Sports department orders 94 sets of equipment at $67 per set. Calculate: 94×67. Regrouping carefully: 94×7=658, 94×60=5,640. Total budget needed: $6,298! 🏈
Reading Challenge
86 participants read 75 pages each for a challenge. Total pages: 86×75. Work through: 86×5=430, 86×70=6,020. Grand total: 6,450 pages read by the group! 📚
Read the problem twice, underline important numbers, and circle what you need to find. Clear problem setup leads to correct solutions!
Rushing through regrouping in word problems. Take your time - accuracy matters more than speed!
From business planning to construction to cooking for large groups - regrouping multiplication is everywhere!
Create your own word problems based on real situations in your life. Make math personally meaningful!