Tim is a postman who works at a local post office. The basic postage is $1.25 and covers any letter that is lighter than 7.5 grams. Emma mailed a letter that weighs 12.92 grams. Comparing to the weight covered by basic postage, Emma’s letter is ____________grams heavier than the prescribed weight

The correct answer is: 5.42 gm

Now as we know that here we have to find the step by breaking one number. The fact that there are no steps to memorise is one of the best things about mental math. The "friendly number" addition approach facilitates working with large numbers. This is due to the fact that we are, in essence, decomposing the problem into more manageable components.
Here we will use some properties which are:

• Commutative Property of Addition: if a and b are real numbers, then a+b=b+a
• Associative Property of Addition: if a,b, and c are real numbers, then (a+b)+c=a+(b+c)
• Compensation Property: It is a mental math strategy for multi-digit addition that involves adjusting one of the addends to make the equation easier to solve.

Now we have given 12.92 – 7.5, let's solve this.
12.92 – 7.5
= 12.92 – 8 (rounding to the nearest whole number)
= 4.92 + 0.5 (compensation)
= 5.42
Emma’s letter is 5.42 grams heavier than the prescribed weight.

Here the concept of Break Apart Numbers is used where a number is divided in two parts to make addition easy. The concept of friendly numbers is also used so that it becomes easy for addition or subtraction purpose. Emma’s letter is 5.42 grams heavier than the prescribed weight.