To add 6.53 + 1.28, adjust 1.28 to make it
easier to add.

7.81 is the answer

Step-by-step explanation:

If you move the "." being the decimal in 1.28 to the end, you make it 128.

Then you take the "." in 6.53 to the end and get 653

add 128 and 653 to get 781.

When you are done, you take the decimal at the end and move it to the left two places to get 7.81

answer: all the values are within because it has a pattern that repeats from -6 to 4.

good luck!