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

To subtract 81 from 304 mentally, round 81 to 80, subtract from 304 to get 224, and then add 1 to compensate for the rounding, giving a final answer of 225.

Step-by-step explanation:

To calculate 304-81 mentally, we can use the strategy of rounding and compensating. First, we can round 81 up to a number that is easier to subtract from 304, such as 80 or 100, and then we adjust the final result to account for the rounding. Here's how to think through it:

The coherent sequence of equations that correspond to this reasoning would be:

This mental math strategy involves rounding and compensation, which allows us to handle subtraction problems quickly without having to use the standard subtraction algorithm. Checking that the answer makes sense in the context of the original problem is a good practice to ensure accuracy.

Answer 2

The required way is shown above.

Step-by-step explanation:

Consider the provided calculation.

304 – 81 is very close to 304 – 100,

Now subtract 100 from 304 mentally, it will gives us 204

Now add 19 as we round 81 to 100.

204 + 19 = 223

So, the answer is 223.

Now write a coherent sequence of equations that correspond to your reasoning.

304 – 81 = 304 – (100 – 19)

= (304 – 100) + 19

= 204 + 19 = 223

Hence, the required way is shown above.