Posted by leya on Thursday, May 24, 2012 at 9:41pm.
Gustav is using frontend estimation. In estimating seventytwo point nine three minus thirtytwo point zero seven, Gustav follows the steps below. Where did he go wrong?
Step 1: seventytwo minus thirtytwo equals forty
Step 2: zero point nine three minus zero point zero seven is approximately equal to one
Step 3:forty minus one equals thirtynine
Step 4: seventytwo point nine three minus thirtytwo point zero seven is approximately equal to thirtynine

math  MathMate, Friday, May 25, 2012 at 7:28am
"Step 3:forty minus one equals thirtynine "
We add the integer and decimal portions, not subtract.