3rd Grade Multiplying by Multiples of 10 Quiz: 10 Questions with Explanations

A \(210\)B \(21\)C \(2{,}100\)D \(37\)

3 boxes of 7 tens is 21 tens, which is 210. Forgetting that rods are tens gives 21.

A \(24\)B \(240\)C \(2{,}400\)D \(64\)

4 x 6 = 24, so 4 x 6 tens = 24 tens = 240. Answer 24 forgets the tens.

A \(30\)B \(3{,}000\)C \(300\)D \(56\)

6 x 5 = 30, so 30 tens = 300. The basic fact ends in 0, so the product ends in two zeros.

A \(7\)B \(70\)C \(700\)D \(49\)

7 x 7 = 49, and 49 tens is 490. So the missing number is 70, not 7.

A 27 beadsB 270 beadsC 2,700 beadsD 39 beads

9 x 3 = 27, so 27 tens = 270 beads.

A \(46\)B \(200\)C \(240\)D \(2{,}400\)

Six jumps of 40 is 6 x 40. 6 x 4 = 24, so 24 tens = 240.

A \(56 \text{ ones}\)B \(15 \text{ tens}\)C \(8 \text{ tens}\)D \(56 \text{ tens}\)

8 x 7 = 56, and 70 is 7 tens, so the product is 56 tens (560).

A \(5 \times 60\)B \(7 \times 40\)C \(3 \times 90\)D \(9 \times 30\)

5 x 60 = 300, 7 x 40 = 280, 3 x 90 = 270, 9 x 30 = 270. 300 is the greatest.

A 720 marblesB 72 marblesC 7,200 marblesD 98 marbles

8 x 9 = 72, so 72 tens = 720 marbles.

A \(6 \times 50\)B \(4 \times 80\)C \(7 \times 60\)D \(9 \times 40\)

9 x 4 = 36 tens = 360. The others are 300, 320, and 420.