Question 20
Maria makes marble patterns with 1 marble in step 1, 5 in step 2, 9 in step 3, and four more in each new pattern. She uses all her marbles to finish step 9. How many marbles does she have in total?
Clarification: all nine patterns are kept separately, as intended by the supplied answer key; the same marbles are not reused between steps.
Clarification: all nine patterns are kept separately, as intended by the supplied answer key; the same marbles are not reused between steps.