Question

Find each quantity without using a calculator. \(\frac{1}{10}\) of 645

Short answer

64.5

Step-by-step solution

Understand the Problem

The task is to find \(\frac{1}{10}\) of 645 without using a calculator. This means you need to divide 645 by 10.

Setup Division

Set up the division problem as follows: \(\frac{645}{10}\). Another way to view it is to move the decimal point one place to the left.

Perform the Division

Since dividing by 10 involves shifting the decimal point to the left, move the decimal point in 645 one place to the left to get 64.5.

Key concepts

fractions

Understanding fractions is essential to solving problems like \(\frac{1}{10}\) of 645. A fraction represents a part of a whole. In this case, \(\frac{1}{10}\) signifies one part out of ten equal parts. When we want to find a fraction of a number, we are essentially dividing that number by the denominator of the fraction.
For instance, to find \(\frac{1}{10}\) of 645, we are dividing 645 by 10. Fractions can also be visualized; imagine splitting a pie into ten equal slices. Taking one slice would mean you have \(\frac{1}{10}\) of the pie.
Similarly, dividing 645 into ten parts will give us our fraction of the whole number. This understanding makes the concept of fractions in division problems much clearer.

decimal point shift

One useful trick in division, especially when dealing with multiples of 10, is shifting the decimal point. This method is quick and helps in avoiding complex calculations.
To divide a number by 10, you simply move the decimal point one place to the left. For example, in the problem of finding \(\frac{1}{10}\) of 645, we can represent 645 as 645.0 (since every whole number can be thought of as having a decimal point at the end).
By shifting the decimal point one place to the left, 645.0 becomes 64.5. Therefore, \(\frac{1}{10}\) of 645 is 64.5. This method allows you to see the relationship between division and decimal placement more clearly. It's a handy tool for quick mental math.
This simple trick is crucial for efficient calculations and is widely used in various mathematical problems.

division without calculator

Performing division without a calculator can be intimidating, but understanding a few basic principles makes it manageable. Let's explore how to divide a number by 10 without using any electronic aid.
First, write down the number clearly. In our example, the number is 645. Think about what it means to divide by 10. Essentially, you are finding out how many groups of 10 fit into 645.
Moving the decimal, as previously described, is the key here. Visualize or write down 645 as 645.0, then move the decimal one place to the left to get 64.5. This represents 10 groups fitting into 645, leaving us with 64.5 as the result.
Practice similar problems to build confidence and proficiency. For example, dividing 830 by 10 would give 83.0 (or just 83) using the same decimal point shift.
These strategies make the division process straightforward and enhance your problem-solving skills without always relying on a calculator.