# How do you complete the pattern with the next two numbers. 10, 15, 21, 28,?

Oct 27, 2016

The pattern seems to be ${a}_{n} = {a}_{n - 1} + n$, with ${a}_{4} = 10$ as the first term

#### Explanation:

According to the formula above:

${a}_{4} = 10$

${a}_{5} = {a}_{4} + 5 = 10 + 5 = 15$

${a}_{6} = {a}_{5} + 6 = 15 + 6 = 21$

${a}_{7} = {a}_{6} + 7 = 21 + 7 = 28$

So the next two numbers are:

${a}_{8} = {a}_{7} + 8 = 28 + 8 = 36$

${a}_{9} = {a}_{8} + 9 = 36 + 9 = 45$