# Arithmetic

Arithmetic is the branch of mathematics that deals with the study of numbers. This is a very broad category, and most people learn arithmetic in elementary school in the context of the use of one or more of the basic operations on numbers. However, arithmetic is a necessary part of virtually all aspects of mathematics such as algebra, geometry, number theory, and more, some of which require much deeper mathematics to solve.

The basic arithmetic operations are addition, subtraction, multiplication, and division.

## Arithmetic in everyday life

Even for those who may not be interested in studying more complicated mathematics, arithmetic is something that most people will use in their day-to-day activities.

### Time

One way that people commonly use arithmetic is when telling time. When someone says "quarter past 1" for example, that means adding 15 minutes to 1 pm, meaning that the time is 1:15 pm. Setting an alarm is another example. If someone who is going to bed decides that they want 8 hours of sleep, they need to add 8 hours to their current time.

### Shopping

Shopping is another common activity in which many people may use arithmetic. If someone is shopping on a budget of \$50, whether it be for groceries, clothing, or something else, they need to sum the cost of each item they want to purchase and ensure that it costs less than \$50. They could also subtract the price of each item they plan to buy from \$50 to make sure it doesn't go below 0.

Another way arithmetic may be used in shopping is for determining how much something costs after a sale. With some understanding of percentages, if something has a 10% off sale, we can find out how much the item costs by either multiplying by 0.9, to take 90% of the price of the item, or multiplying by 0.1, then subtracting the result from the original price.

### Cooking

There are many different ways a person may use arithmetic during cooking. Ratios and proportions are very common in cooking, and adjusting them to suit your particular needs can involve the use of arithmetic. For example, if a cookie recipe is meant to make 32 cookies, but 32 is too many cookies, halving (multiplying by ½ or dividing by 2) each ingredient would yield half the number of cookies.