Multi-Step Multiply & Divide
Solve problems involving multiplication and division, including scaling problems and correspondence problems where n objects are connected to m objects
Ce que l'enfant saura faire ensuite
- Solve a scaling problem (e.g. 'the ribbon is 3 times as long')
- Solve a correspondence problem (e.g. '4 shirts and 3 trousers: how many outfits?')
- Solve a missing-number multiplication or division problem
1 · Lis
Some problems need two steps, not one. A ribbon might be described as '3 times as long' as another one, that's a scaling problem. Or two groups of things might get matched together, like shirts with trousers, that's a correspondence problem. Once you know which kind of problem it is, you know which operation to use.
Zara has 4 shirts and 3 pairs of trousers. Any shirt can go with any pair of trousers. To find how many outfits she can make, multiply the two numbers: 4 x 3 = 12 outfits.
If a number is missing from a multiplication, use division to find it, and the other way round. For 3 x ? = 15, work backwards: 15 / 3 = 5.
Scaling means multiply by how many times bigger. Matching means multiply the two group sizes. A missing number problem uses the opposite operation to find the answer.
À lire aussi
Count by units of 7 to multiply and divide by using arrays and tape diagrams
Scaling means making something so many times as big. A ribbon 3 times as long as 12 cm is 3 x 12 = 36 cm. Arrays show scaling as extra rows, and tape diagrams show it as extra bars. However you draw it, times as many means multiply. Spot the scale word and the operation is decided.
Ways to divide greater numbers
Correspondence problems pair two lists together. Four shirts and 3 trousers make 4 x 3 = 12 outfits, one for every pairing. Listing every pair proves the total. Missing-number problems work backwards from the same idea: 7 x ? = 42 asks which number pairs with 7 to make 42. Division finds it.
1.4 Multiply Whole Numbers
Two-step problems chain multiplications together. Six boxes with 4 toys in each hold 6 x 4 = 24 toys, and half of them being cars gives 24 / 2 = 12 cars. Each answer feeds the next step. Writing both steps down keeps the chain unbroken. Solve in order and check at the end.
1.5 Divide Whole Numbers
Division undoes multiplication, which solves missing-number puzzles. For 48 / ? = 8, ask which number times 8 makes 48. Since 6 x 8 = 48, the missing number is 6. Table facts run both ways: every multiplication hides two divisions.
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