There are between 60 and 100 children at the sunny side holiday camp. When the children are put into pairs, there is 1 child lef
t. When they are put into groups of 5, there is 1 child left. When they are put into groups of 8, there is 1 child left. How many children are there at the camp ?
third choice : Let 2a + 1 be one odd number, and let 2b + 1 be the other odd number. (2a + 1) + (2b + 1) = 2a + 2b + 2 = 2(a + b + 1). Because 2(a + b + 1) is evenly divisible by 2, it is an even number.