Unknown Quantity Words

Free interactive math game: Unknown Quantity Words — Start/Change unknown. Part of the Addition & Subtraction category on MathKite.

Example problems

Taken from the generator that powers this exercise. A fresh set appears every time the page is opened, and the printable worksheet holds ten of them.

  1. Anna had some stickers. Her friend gave her 19 more, and now she has 49. How many did she start with?
  2. Tom had 29 marbles. He lost some, and now he has 10. How many did he lose?
  3. Tom had 29 marbles. He lost some, and now he has 23. How many did he lose?
  4. Anna had some stickers. Her friend gave her 28 more, and now she has 63. How many did she start with?

About this exercise

Finding a missing amount in a story, which is algebra before the letters arrive.

How to solve it

Write the story as a number sentence with a gap, then work out what fills the gap. Starting amount, change and result are the three parts.

Worked example

Tom had 20 marbles and now has 15, so 20 - ? = 15 and he lost 5.

Common mistake

Answering with a number already given in the story. The answer is the part that was never stated.