16
83 + 17 = 100
1
If a number is added to itself, it is twice that number → 18 ÷ 2 = 9 → 9 + 9 = 18
7/10 must be added to 3/10 to make a whole number, 1.
6
You write: eight hundred and eighty dollars. Always do it as close to the square where you write in the number and draw a line in front of the eight hundred. This way it can't be added to or changed to a higher number.
30 + 70 = 100
83 + 17 = 100
1
If a number is added to itself, it is twice that number → 18 ÷ 2 = 9 → 9 + 9 = 18
7/10 must be added to 3/10 to make a whole number, 1.
Placing a question mark at the end of a number does not make it a sensible question.
6
Seven
21
56
408 is the ans