What do you understand by 15?
In mathematics, 15 is a number that comes with a value for something. In real life, it can be expressed as a count of a number of items as well. 15 is used for various arithmetic operations such as addition, subtraction, multiplication and division. The number 15 is highly essential for both mathematical and daily life purposes.
Use of a Number Fifteen in Real life
Here are some real life examples of 15:
- Alice bought 15 chocolates for her friends in school.
- Mrs Harriet paid $15 to the grocery store.
- The tailor cut 15 inches of cloth.
How to write 15 in Words?
15 in words is written as ‘fifteen’.
How to represent 15 in the Place Value Chart?
As we have seen, 15 is a two-digit number. Hence, it will have a place value for 2 digits only. The place value of digits from right to left is as follows:
Now, when we represent 15 in a place value chart, this is how it looks:
Tens | Ones |
|---|---|
1 | 5 |
Here, 5 is in the ones place and 1 is in the tens place.
Solved Examples
Example 1: Expand 15 as per the place value chart.
Solution: Since 15 is a two digit number, the place values involved for the digits are ones and tens.
Tens | Ones |
|---|---|
1 | 5 |
During the expansion of a number we multiply 1 with ones place digit, 10 with tens place digit, 100 with hundred place digit and so on.
Here, 5 is in ones place and 1 is in tens place
10 x 1 + 1 x 5
⇒ 10 + 5
so, the expanded form of 15 is 10 + 5.
Example 2: Jennifer bought 15 pairs of socks for herself. Each pair costs $2. What is the total cost of the socks?
Solution: Pairs of socks Jennifer bought = 15
Cost of each pair of socks = $1
To find the total price, we have to add ‘2’ 15 times.
Thus, 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 = 30
Total price of 15 pairs of socks is 30 dollars.
Example 3: David, Barney and Fanny are participating in a relay race in their school. David will run for 5 miles and pass the baton to Barney who will run for 5 miles and then finally will pass the baton to Fanny until she reaches the final. Show the distance covered by them on a number line.
Solution: Here, it is given that David, Barney and Fanny will run an equal distance of 5 miles each in the relay race. We can show this on a number line.
As you can see, each of them participating in the relay race will cover 5 miles each and if we add them up together, it will give us 15 miles in total.
No, 15 is not a prime number but a composite number with more than two factors, that is, factors of 15 are 1, 3, 5 and 15.
The number 15 can be expressed as the following forms:
15 is a whole number
15 is a natural number
15 is a counting number
15 is an odd number
15 is a composite number
The sum of the digits of 15 can be expressed as,
1 + 5 = 6
15 is not an even number as it is not completely divisible by 2.