Length Word Problems

Two pieces of string laid end to end make one longer piece. Lengths add.

And they take away

Cut a piece off and the string gets shorter by exactly that much.

Same units only

You can only add lengths in the same unit. Centimetres go with centimetres.

Draw the bars first. The picture shows whether to add or subtract.

Decide what the story is asking

Length problems come in three flavours. How long altogether means add. How much longer means subtract. How long was it before it was cut means add the piece back on. Read to the end of the problem and name the flavour before touching the numbers.

Draw the lengths as bars

Sketch each length as a bar, roughly to size, with its number written on it. A problem that looked confusing in words usually becomes obvious as a picture, because you can see whether the answer should be bigger or smaller than the numbers given.

Answer with a unit

The answer to a length problem is a length, so it needs a unit. "12" is not an answer; "12 centimetres" is. Check that your unit matches the one the problem used, and that your number is sensible — a pencil is not 12 metres long.