@PicturesFoIder Round off to the nearest 10 for both by adding 3 and 2 to the numbers
=(27+3) + (48 + 2)
= 30 + 50
This is much easier to compute than 27 + 48. So you add them up and you get 80 but you need to subtract what you added to the numbers.
= 80 - 3 -2
= 75
It’s a 2 second calculation