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Question 1 of 6
1 of 6
Starting with the smallest triangular number, order these numbers so they form the sequence of triangular numbers in ascending order.
Click and drag answers to change the order, or select using Tab then move by pressing Space and the arrows on your keyboard.
10
15
6
21
3
1
Triangular numbers can be represented by an array of dots in a triangle shape where each row increases by 1 each time.