Unknown in Multiplication & Division
Determine the unknown whole number in a multiplication or division equation relating three whole numbers (e.g. 8 × ? = 48, ? × 6 = 42)
What a learner can do afterwards
- Find the missing factor in 7 × ? = 63
- Find the missing dividend in ? ÷ 5 = 9
- Explain the strategy used (e.g. using the related multiplication fact)
1 · Read
Sometimes a multiplication or division sentence has one number missing, shown as a question mark. It might look like 8 × ? = 48, or ? ÷ 6 = 7. Your job is to figure out what number belongs there.
Look at 7 × ? = 63. You already know that division undoes multiplication, so 63 ÷ 7 tells you what number times 7 makes 63. That means ? = 9.
Now look at ? ÷ 5 = 9. Some number split into 5 equal groups makes 9 in each group. Multiply back: 5 × 9 = 45. So ? = 45.
Always check your answer by putting it back into the original sentence. If both sides match, you found the right number.
Find a missing number by using the multiplication fact you already know, then check it by multiplying back.
More to read
Multiplication equations
Equations are sentences with numbers. The equals sign says both sides balance. In 7 x ? = 63 the missing factor must make the sides match.
Use the related fact to fill gaps. Since 7 x 9 = 63, the missing number is 9.
Ways to divide greater numbers
Greater numbers divide best in stages. Break the total into place value parts, divide each part, and add the answers. This works because division shares each part fairly.
Check with multiplication at the end. Multiply your answer by the divisor and you should land back on the starting number.
1.5 Divide Whole Numbers
Division splits a total into equal groups or shares. When you see 20 ÷ 5, ask how many groups of 5 fit inside 20. The answer is 4, because 4 groups of 5 make 20.
Division always pairs with a multiplication fact. If you know 7 x 8 = 56, then you also know 56 ÷ 7 = 8. Learning them together cuts your work in half.
Explore more
2 · Watch
En anglaisTake it off screen
Where it sits
This opens up
17 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.