5. Multiply 2 digits x 1 digit by decomposition. A) 36 × 2 = B) 45 × 3 = C) 13 × 5 =

To solve these multiplication problems using decomposition, we break down the two-digit numbers and then multiply the components by the one-digit number. Let's go through each problem step by step:
A) 36 × 2

Decompose 36 into tens and ones: 36 = 30 + 6 .
Multiply each part by 2: $30 \times 2 = 60 and $6 \times 2 = 12 .
Add the results: 60 + 12 = 72 .

So, 36 × 2 = 72 .
B) 45 × 3

Decompose 45 into tens and ones: 45 = 40 + 5 .
Multiply each part by 3: $40 \times 3 = 120 and $5 \times 3 = 15 .
Add the results: 120 + 15 = 135 .

Thus, 45 × 3 = 135 .
C) 13 × 5

Decompose 13 into tens and ones: 13 = 10 + 3 .
Multiply each part by 5: $10 \times 5 = 50 and $3 \times 5 = 15 .
Add the results: 50 + 15 = 65 .

Therefore, 13 × 5 = 65 .
By decomposing the numbers, we simplify the multiplication process which makes it easier, especially when handling larger numbers.

Answered by IsabellaRoseDavis | 2025-07-21