Question

Veronica has to multiply 398 x 18. She says she can multiply 400 X 18 and then take
away one group of 18.

Write an expression that shows Veronica's thinking

Answer 1

Answer:

See below.  Veronica's thinking is incorrect.  I've included what she is thinking, but the correct thinking is more useful, as noted below.

Step-by-step explanation:

398 is 2 less than 400.  Veronica needs to remove two groups of 18.

I don't know what Veronica is thinking, other than:

(398 x 18) = (400*18 - 18)

She should be thinking:

(398 x 18) = (400 x 18) - (2*18).  The "2" is for the two extra groups of 18 that she will have when multiplying 400 x 18, instead of 398 x 18.