Question

Describe a way to calculate 304-81 mentally by using reasoning other that the common subtraction algorithm. Then write a coherent sequence of equations that correspond to your reasoning

Answer 1

See explanation

Explanation:

To subtract mentally 81 from 304, complete following steps:

Step 1: Write number 304 as

`304=300+4\\ \\304=200+100+3+1\\ \\304=200+20+80+3+1`

Step 2: Write number 81 as

`81=80+1`

Step 3: Now subtract 80 and 1 from number 304:

`304-81=(200+20+80+1+3)-(80+1)\\ \\304-81=200+20+3\\ \\304-81=223`