Missing factor problems: what they are and how to help
How to help Grade 3 children solve missing factor problems like 4 × ? = 24, and why they matter for learning division.
A missing factor problem gives the answer and one of the numbers, and asks for the other: 4 × ? = 24. Children often find these harder than ordinary facts, because they cannot simply recite.
Why schools teach them
Missing factor problems are division in disguise. Asking "4 times what is 24?" is the same as asking "24 divided by 4?". Children who are comfortable with missing factors usually find division much less of a jump.
Three ways to solve them
- Skip count: count in fours until you reach 24, keeping track of how many jumps.
- Draw it: draw 4 groups and share 24 dots between them.
- Use a known fact: "I know 4 × 5 = 20, and 24 is one more four, so it is 6."
The third strategy is the goal, but the first two are fine while children build confidence.
Common mistakes
- Adding instead of multiplying: answering 20 because 4 + 20 = 24.
- Guessing without checking. Always ask your child to put their answer back into the sentence.
Talk about it
Ask your child to explain how they found the answer. A child who says "I counted in fours" is learning just as much as one who knows the fact instantly.