=EVEN(number) rounds up (away from zero) to the next even whole number, and =ODD(number) to the next odd one. EVEN(3) is 4, EVEN(4.1) is 6, ODD(-2.1) is -3. Use them when things come in pairs, like seats at tables for two.
=MOD(number, divisor) returns the remainder after dividing. MOD(17,5) is 2. It answers practical questions:
- leftovers: 17 eggs into boxes of 6 leaves MOD(17,6) = 5;
- every Nth item:
MOD(A2,3)=0 is TRUE for rows 3, 6, 9...;
- odd or even:
MOD(B2,2)=1 for odd numbers (ISODD and ISEVEN do this too).