Testinar Grade 3 math

Multiplying by Multiples of 10

Students will multiply one-digit numbers by multiples of 10 using place value and known multiplication facts.

CH02-03 Number and Operations in Base Ten

Directions Solve each problem. Show your reasoning on the page or on separate paper. Check the answer key only after finishing.

What is \(6\times40\)? Show your thinking: \(6\times40 = 6\times(4\times10) = (6\times4)\times10\).
1. \(46\)
2. \(64\)
3. \(240\)
4. \(2400\)
How many stars are there? Skip count by \(10\)s to find the total.
1. \(13\)
2. \(103\)
3. \(31\)
4. \(30\)
Which repeated addition matches \(5\times10\)?
1. \(5+5+5\)
2. \(10+5\)
3. \(10+10+10+10+10\)
4. \(5+10\)
Quinn calculated \(7\times30\) and got \(710\). What error did Quinn make?
1. Quinn forgot to multiply at all.
2. Quinn wrote the zero in the wrong place.
3. Quinn multiplied correctly but added an extra zero.
4. Quinn wrote down the digits \(7\) and \(30\) instead of multiplying them.
This array has \(2\) rows. Each row has \(50\) squares. How many squares in total?
1. \(52\)
2. \(25\)
3. \(100\)
4. \(1000\)
Which shows why \(4\times20\) equals \(80\)?
1. \((4+2) \times 10 = 60\)
2. \(4 + 2 + 10 = 16\)
3. \(4 \times (2+10) = 48\)
4. \((4\times2) \times 10 = 8 \times 10 = 80\)
Sam has \(8\) groups of \(10\) stickers. How many stickers does Sam have in total?
1. \(18\)
2. \(108\)
3. \(810\)
4. \(80\)
Look at this number bond. What value should replace the question mark?
1. \(6\); divide by \(10\)
2. \(600\); multiply by \(10\)
3. \(60\); add
4. \(10\); multiply

Teacher and parent reference

Answer key and explanations

C. \(240\)
Multiply \(6\times4=24\), then multiply by \(10\) to get \(240\): \(6\times40 = 24\times10 = 240\). You decompose \(40\) as \(4\times10\), then use the associative property.
D. \(30\)
Skip count by \(10\)s: \(10, 20, 30\). There are \(3\) groups of \(10\) stars, so \(3\times10=30\) stars total.
C. \(10+10+10+10+10\)
\(5\times10\) means \(5\) groups of \(10\), which is the same as adding \(10\) five times: \(10+10+10+10+10=50\). This shows that multiplication is repeated addition.
D. Quinn wrote down the digits \(7\) and \(30\) instead of multiplying them.
\(7\times30=210\) (multiply \(7\times3=21\), then multiply by \(10\)). Quinn wrote \(7\) and \(30\) together as \(730\) instead. The correct answer is \(210\).
C. \(100\)
\(2\) rows of \(50\) squares \(= 2\times50=100\) squares. Multiply \(2\times5=10\), then multiply by \(10\) to get \(100\).
D. \((4\times2) \times 10 = 8 \times 10 = 80\)
\(4\times20 = 4\times(2\times10) = (4\times2)\times10 = 8\times10 = 80\). This uses associative property: you break \(20\) into \(2\times10\), multiply the single digits first, then multiply by \(10\).
D. \(80\)
\(8\) groups of \(10 = 8 \times 10 = 80\) stickers. The place-value chart shows 8 tens and 0 ones, which equals 80.
D. \(10\); multiply
\(60 = 6 \times 10\). The number bond shows that \(60\) can be decomposed into \(6\) and another factor; that factor is \(10\). You multiply \(6\times10\) to get \(60\).