Question

How can you express 499 to find the product 499X5 using mental math? Explain.

Answer 1

2 ways

anything times 5 can be found by halving the number and multiplying by 10
so we get 249.5 times 10 or 2495

or, we can do
499=500-1

so
499 times 5=(500-1)(5)=5(500-1)=5(500)+5(-1)=2500-5=2495