googoodan.comA little practice. A big discovery.
Subtraction · Grade 1

Change Unknown Word Problems: How Many Were Spent?

A story can tell you how much there was before and how much is left, while leaving out what happened in between. Find the amount spent by connecting the starting amount, the change, and the amount remaining.

6 problemsAnswer key includedFree printableA4 & US Letter
Generate & printSee the worked example

The amount left is not the amount spent

Alex has 16 cents set aside for school supplies. After a purchase, 7 cents remain. When asked how much was spent, a child may copy 7 because it appears near the question. Seven is useful information, but it names the money left, not the money that was spent.

Before: 16 cents.

Spent: an unknown amount.

After: 7 cents remain.

16 − ? = 7
16 − 7 = 9

Alex spent 9 cents. The 9 cents spent and the 7 cents remaining account for all 16 cents.

Make both parts visible

Use sixteen counters, with each counter representing one cent. Move seven into a small area labeled “left.” The other nine counters represent the amount spent. The counters are a model of the quantities; children do not need to identify different coins to use this worksheet.

The starting amount is the whole. Money spent and money remaining are its two parts. Subtracting the known part from the whole finds the missing part. This is why 16 − 7 answers the question even though the events in the story could be written as 16 − ? = 7.

Count up to check the difference

Another way is to count from seven up to sixteen: three more reaches ten, and six more reaches sixteen. Three plus six is nine. Ask what the nine counts. It is the gap between the ending and starting amounts, not a new amount that was added to Alex’s money.

If the child writes 23: read the two quantities with their labels. Sixteen was all the money at the start, and seven is part of that same money. Adding them counts the remaining money twice. Put the counters back into one starting collection and separate it into spent and left.

Keep the question attached to the answer

Have the child finish the sentence “Alex spent ___ cents.” Then check that spent plus left equals the starting amount. A completed equation such as 9 + 7 = 16 is a valid check even though the answer key shows subtraction.

These six questions focus on the unknown change in a spending situation. All quantities are below twenty. They are not a coin-identification activity or a worksheet about finding change from a cashier.

Make a practice set

Choose what to print. Selecting both shows the answer key on screen and prints the questions followed by the answers.

Print materials

After the practice

Ask the child to point to the amount spent and the amount left in a counter model. If the equation is correct but the answer names the wrong quantity, return to the question rather than repeating the calculation.

More about subtraction · Grade 1 worksheets

Grade 1 selected skill connection: 1.OA.A.1 (change-unknown subtraction stories). See the Common Core grade guidance. This worksheet does not cover every requirement in the standard.