how do you do the counting up method

Answer 1

this is used many times for subtraction.

lets take the example 198 - 46. 198 rounds up to 200, and 46 rounds up to 50. 200 - 50 = 150. However, that's not our answer. 198 = 200-2. so the answer would be -2 added to 150. Also, 46 is 50-4. So the answer would be another +4 to 150. Thus 150-2+4 = 152.