IMO Practice Test — Addition Strategies
6 Questions • 12 min • Olympiad level
12:00
Question 1 of 6
hard
Compensation: 38+29. Think 38+30 then adjust.
56
67
68
77
Explanation: 38+30=68 then -1=67
Question 2 of 6
medium
Quickest strategy for 50+50?
Count on
Make 10
Doubles
Compensation
Explanation: 50+50 is doubles
Question 3 of 6
medium
Near doubles: 14+15=?
27
28
29
30
Explanation: 14+14=28 so 14+15=29
Question 4 of 6
hard
Make-10: 37+6 = (37+3) + ?
40+3=43
40+4=44
41+2=43
None
Explanation: 37+3=40 then +3=43
Question 5 of 6
hard
Which additions all give 50? A:25+25 B:30+20 C:45+5 D:40+10
A and B only
B and C only
A B C and D
B C and D only
Explanation: All equal 50
Question 6 of 6
easy
Doubles fact for 8 helps which problem?
8+7
8+9
8+8
8+4
Explanation: 8+8=16 is the doubles fact