SSC Exam » SSC Study Materials » Reasoning » Counting of Odd Days

# Counting of Odd Days

Counting of odd days is done by using various formulas. This article aims to highlight some of these techniques that will help you to solve this question with absolute ease.

Odd days can be effectively counted concerning a particular year by using various mathematical techniques. Normally, a year has a total of  365 days which can also be written as 52 weeks and one day, (52 × 7) + 1. An extra day along with the 52 weeks, is called an odd day. Counting the number of odd days in a year depends on whether the year is a leap year or a non-leap year.

Similarly, if we talk about a century, i.e., 100 years, then a century has a total of 76 non-leap years and 24 leap years. Counting of odd days in a century shall be as follows:

24 non-leap 6 × 1 = 124 odd days.

## Counting the number of odd days in a year

Since an ordinary or non-leap year has 365 days in total, it has one odd day. But if a leap has 366 days, then the number of odd days increases by one, so a leap year has a total of two odd days.

When you divide 365 by 7, you get 1 as a residual in an average year of 365 days. A non-leap year, therefore, has one odd day.

When we divide 366 by 7, we get 2 as the remainder, indicating that a leap year has 2 odd days.

If you’re asked to count the number of odd days from the year 2007, what will be the answer? If you can calculate now itself, then well and good, otherwise we’ll be solving the same question once we’ve discussed other details too.

## Counting of odd days in a century

A century (100 years) comprises 76 non-leap years and 24 leap years. So, the number of odd days in a century shall account for 124 days. The detailed calculation is given as:

76 × 1 + 24 × 2 = 124 odd days = 17 weeks + days = 5 odd days in a century.

Counting of odd days in 200 years = 5 × 2, which will give an equal of 3 odd days in 200 years.

Counting of odd days in 400 years = 5 × 4 + 1, which will give 0 odd days in 400 years.

Similarly, odd days are related to the week of the days as well.

Days of the week

No. Of odd days

Sunday

0

Monday

1

Tuesday

2

Wednesday

3

Thursday

4

Friday

5

Saturday

6

Number of odd days in a month

Months

Days

Odd days

Jan, Mar, May, July, Aug, Oct, Dec

31

3

Feb (Non-leap year)

28

0

Feb (Leap year)

29

1

Apr, Jun, Sept, Nov

30

2

## Important points to Remember

counting the number of odd days in a year can become quicker and easier by following some shortcut tricks given below.

• When counting odd days equals zero between any two months in one year, the day if the dates will also happen to be the same.

Non-leap year

Leap year

Jan- Oct

Jan- Apr

Feb- Mar

Jan- July

Feb- Nov

Feb- Aug

Mar- Nov

Mar- Nov

Apr-July

Apr- July

Sep-Dec

Sep-Dec

• The calendar tends to repeat itself after every 400 years. For example, if it happens to be a Monday on 3 Aug 2003, then it will be Monday on 3 Aug 2403 as well as 3 Aug 2803.
• When we talk about the first day of a century, then it must either be Monday, Wednesday, Friday or Saturday. Similarly, while considering the last day of a century, it can never be one of the following days, Tuesday, Thursday, or Sunday.
• There are zero odd days in 400 years, there is a single odd day in 300 years, then a total number of odd days in 200 years equals 3, and there are a total of 5 odd days in a century or 100 years.

While solving problems related to counting the number of odd days in a year, you can easily check and eliminate the wrong options by using the above shirt tricks. It will save you a lot of time that can be used in lengthier questions that involve longer solutions.

Let’s summarise all that we have understood so far by solving an example.

Get answers to the most common queries related to the SSC Examination Preparation.

## How many odd days were there in 1800?

Ans : In 200 years, there are a total of 10 odd days (5 × 2), that is 1 week and 3 odd days. There...Read full

## How many odd days are there in 67 days?

Ans : This question holds a pretty easy solution to it. Look, 67 days can also be written as 9 week...Read full

## What year can you reuse calendars?

Ans : Yes, the old calendars that we throw away as wastage can be reused. All you need to know is t...Read full

## When can I reuse my 2002 calendar?

Ans : You can reuse the 2002 calendar in the following years again and again. The years are as foll...Read full