I did something a bit more targeted, useful for carrying and mental arithmetic—“Remember this number. Okay, now add these two other numbers. What was the answer? What was the number you had to remember?” This also had the benefit of turning a wheels-spinning slow answer on the arithmetic problem into an actual wrong answer on the remembering problem, instead of just a slower-acquired right answer on the arithmetic problem, which is a lot less visible.
I did something a bit more targeted, useful for carrying and mental arithmetic—“Remember this number. Okay, now add these two other numbers. What was the answer? What was the number you had to remember?” This also had the benefit of turning a wheels-spinning slow answer on the arithmetic problem into an actual wrong answer on the remembering problem, instead of just a slower-acquired right answer on the arithmetic problem, which is a lot less visible.