|
|
 Solution
- The display shows 855.
855 is 20 (2 tens) more than the correct sum 835. Zona must have
pressed a wrong key in the tens place of one of the numbers. In
fact, she pressed 
instead of  for the
first number: 
- The display shows 535.
535 is 300 (3 hundreds) less than the correct sum 835. Zona must
have pressed a wrong key in the hundreds place of one of the numbers.
In fact, she pressed 
instead of  for the
first
number: 
- The display shows 263.
263 is 572 less than the correct sum 835. Zona only pressed one
wrong key, so it must not have been a number key. In fact, Zona
pressed  instead
of  : 
- The display shows 837.
837 is 2 more than the correct sum 835. Zona must have pressed
a wrong key in the ones place of one of the numbers. In fact,
she pressed  instead
of for the second
number: 
Back to Math Mountain
|
|
|
