standard_description: Fluently add and subtract within 20 using mental strategies. (See standard 1.OA.6 for a list of mental strategies.) By end of Grade 2, know from memory all sums of two one-digit numbers.
problem_activity: Task
Decide if the equations are true or false. Explain your answer.
4 x 5 = 20
34 = 7 x 5
3 x 6 = 9 x 2
5 x 8 = 10 x 4
6 x 9 = 5 x 10
2 x (3 x 4) = 8 x 3
8 x 6 = 7 x 6 + 6
4 x (10 + 2) = 40 + 2


aligns: no