Without just going and doing the addition, you can use this formula:
Sum of 1 to N is: (N+1)*N/2. So take sum of [1 to 100], then subtract off the sum of [1 to 20], and you'll have left the sum [21 to 100].
Sum [1-100] = (100+1)*100/2 = 5050. Sum[1-20] = (20+1)*20/2 = 210.
So 5050 - 210 = 4840
100
21
The total is 21.
The numbers are 21, 22 and 23.
There are none.
The numbers are 21, 22 and 23.
5 & 21
The numbers are 20 and 21.
The sum of the first six positive numbers (1 to 6) is 21.
37 + 21 = 5837 - 21 = 16The two numbers therefore are 37 and 21.
The numbers are 26 and 21
The numbers are 11 and 10