A Class III student solved 26 × 5 as follows: 26 × 5 = 1030 Which of the…

Concept

In multi-digit multiplication, regrouping preserves place value. When a product in one place is 10 or more, its ones digit stays in that place and the remaining tens are carried to the next place.

Partial products must then be combined according to their place values; they are not simply written side by side.

Application

1. Multiply the ones: 6 × 5 = 30. Write 0 in the ones place and regroup 3 tens.

2. Multiply the tens: 2 tens × 5 = 10 tens. Add the regrouped 3 tens to obtain 13 tens.

3. Write 13 tens and 0 ones, giving 130. The written result 1030 places the partial products side by side instead of combining them by place value.

Contrast

• Multiplication of a one-digit number by a one-digit number develops the basic products used in each place.

• Recall of multiplication tables helps retrieve 6 × 5 = 30 and 2 × 5 = 10 quickly.

• One-to-one correspondence concerns pairing members of two sets and supports counting relationships.

• Regrouping explains how the partial products are carried and combined across place values.

Cross-check

Using the distributive property, 26 × 5 = (20 × 5) + (6 × 5) = 100 + 30 = 130. This confirms that the concept to revisit is regrouping.