What is the perimeter of a rectangle 15mm by 25mm in centimeters?

Answer 1

375mm2

Answer 2

To answer this question you need to know two things:

1. How do you find the perimeter of a rectangle?

2. How do you convert millimeters into centimeters?

Let's answer the questions in that order. First #1.

The perimeter of a shape is the sum of the lengths of each side. Think of it as taking a string and tracing the outside edges of shape. How long would that piece of string be? That is the perimeter. There is a formula for finding the perimeter of a rectangle: P = 2l + 2w. P is the perimeter, l is the length of the long side of the rectangle, and w is the short side of the rectangle. In English the formula says: the perimeter of a rectangle is equal to twice the length plus twice the width.

For this rectangle, l = 25 mm and w = 15 mm. So using our formula above:

P = 2 * 25 mm + 2 * 15 mm

P = 50 mm + 2 * 15 mm

P = 50 mm + 30 mm

P = 80 mm

So the perimeter is 80 mm. That leads us to #2.

How do you convert mm into cm? Well, mm stands for millimeters. In one meter, there are 1000 millimeters. One millimeter is one thousandth of a meter And cm stands for centimeters. In one meter there are 100 cm. One centimeter is one hundredth of a meter. That means in 100 cm there are 1000 mm. (If that is confusing, think of it this way. Does 1 meter equal 1 meter? Of course! So if 100 cm is equal to 1 meter, and 1000 mm equal 1 meter, it makes sense that 100 cm = 1000 mm).

Since 100 cm there are 1000 mm, one centimeter is the same as 10 millimeter. Put another way, millimeters are ten times smaller than centimeters and centimeters are ten times larger than millimeters. So to convert our 80 mm into cm, we just need to divide it by 10.

80 mm / 10 = 8 cm

So the answer is 8 centimeters.