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

Answer:

A simple way to mentally subtract is to simplify the numbers, subtract, then subtract or add for the simplified answer.

Step-by-step explanation:

A simple way to mentally subtract is to simplify the numbers, subtract, then subtract or add for the simplified answer. For this 304 - 81 is easier as 300 - 80. Make note that we took away 4 from 304 and 1 from 81. Now we just subtract mentally, and 300 - 80 = 220. If we took 4 from 304, this means that our answer should be 4 less, since 4 less would be 304 - 80 = 216. If we took 1 from 81, then we add 1 back to get the equation 304 - 81 = 217.

304 - 81 = ?

300 - 80 = 220

304 - 80 = 216

304 - 81 = 217

Answer 2

Answer:

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.