Multiplying Multi-Digit Whole Numbers: math test solutions, Grade 4 – download the PDF

1 Mental math / 4 pts

1. \(9 \times 7 = 63\), one zero: 630. (1 pt)
2. \(6 \times 8 = 48\), two zeros: 4,800. (1 pt)
3. \(5 \times 4 = 20\), two zeros: 2,000. (1 pt)
4. \(7 \times 3 = 21\), three zeros: 21,000. (1 pt)

2 Area model / 3 pts

Split \(27 = 20 + 7\) and \(45 = 40 + 5\). (1 pt)

Partial products: 800, 280, 100, and 35. (1 pt)

Total: \(800 + 280 + 100 + 35 = 1{,}215\). (1 pt)

3 4-digit times 1-digit / 3 pts

\(6{,}000 \times 7 = 42{,}000\), \(100 \times 7 = 700\), \(30 \times 7 = 210\), \(8 \times 7 = 56\). (2 pts)

\(42{,}000 + 700 + 210 + 56 = 42{,}966\). (1 pt)

4 Two 2-digit numbers / 3 pts

\(83 \times 50 = 4{,}150\). (1 pt)

\(83 \times 7 = 581\). (1 pt)

\(4{,}150 + 581 = 4{,}731\). (1 pt)

5 Reasonable answer? / 3 pts

1. \(40 \times 30 = 1{,}200\). (1 pt)
2. 1,889 is far from 1,200, so Kai’s answer is too big. (1 pt)
3. \(41 \times 29 = 41 \times 30 - 41 = 1{,}230 - 41 = 1{,}189\). (1 pt)

6 Summer camp / 4 pts

1. \(18 \times 64 = 640 + 512 = 1{,}152\) dollars. (1 pt)
2. \(45 \times 29 = 45 \times 30 - 45 = 1{,}350 - 45 = 1{,}305\) dollars. (1 pt)
3. \(1{,}152 + 1{,}305 = 2{,}457\) dollars. (1 pt)
4. \(2{,}500 - 2{,}457 = 43\). The camp has $43 left. (1 pt)