4th Grade Multiplying Multi-Digit Numbers Quiz: 10 Questions with Explanations

A \(120\)B \(70\)C \(1,200\)D \(12,000\)

4 × 3 = 12, and two zeros are attached: 1,200. Forgetting the zeros gives 120.

A \(4,200\)B \(420\)C \(42,000\)D \(607\)

7 × 6 = 42, then attach two zeros: 4,200.

A 65B 85C 15D 75

60 + 15 = 75. Adding the factors in some other way, or using only one part, leads to wrong totals like 15.

A \(4,540\)B \(4,840\)C \(4,940\)D \(5,040\)

4 × 1,000 = 4,000; 4 × 200 = 800; 4 × 30 = 120; 4 × 5 = 20. The sum is 4,940.

A 266B 276C 286D 46

23 × 10 = 230 and 23 × 2 = 46. Then 230 + 46 = 276.

A 350B 280C 3,500D 340

200 + 50 + 80 + 20 = 350. Leaving out one of the four cells gives a smaller total such as 280 or 340.

A \(100 \times 13\)B \(29 \times 13\)C \(4 \times 38\)D \(100 + 13\)

4 × 25 = 100, so by the associative property 4 × 13 × 25 = 100 × 13 = 1,300.

A \(1,800\)B \(2,400\)C \(3,000\)D \(240\)

Round to 60 × 40 = 2,400. The exact product is 2,356.

A 55B 336C 326D 356

48 × 7 = 40 × 7 + 8 × 7 = 280 + 56 = 336. Adding 48 + 7 gives 55.

A \(8,200\)B \(9,800\)C \(1,283\)D \(10,200\)

8 × 1,275 = 8,000 + 1,600 + 560 + 40 = 10,200. Adding 8 + 1,275 gives 1,283.