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August 10, 2023
Here on this page you will get to know about the Number Series formulas with its definition and types. You will also get to learn, How to solve Questions with the help of formulas.
Number series is a sequence of numbers which is framed, using a particular system/rule, in which the numbers are not in a specific order. All we have to do is to find out the system/rule that a particular series is following and finding the number using that system/rule.
For Example : 3, 9, 27, 81 ?
It is Geometric series.
Each term is Multiplied by 3.
So , 81 x 3 = 243
Successive term – Preceding term
Common difference = d = a2 – a1
Types of Number Series is given below:
Add up Series +
These problems are never asked they are very easy, we are talking about them to introduce the number series from basic.
Add up Series –
Square up +(Easy to Identify)
Square up Add up +(Hard to Identify)
Square up Step up +(Very hard to identify not asked mostly unless paper is very tough)
Same for Step Up Series +, but instead of adding, Subtract.
Question : Find the missing number? 99, 121, 143, ___, 187, 199 .
A. 170B. 165C. 158D. 172
Answer : 165
Explanation:The given series is an AP with first term as 99 and common difference as 22.
Question : Find the next term in the series : 51,52,53,55,58,63,____.
A. 69B. 77C. 81D. 71
Answer : 71
Explanation:
Fibonacci series is added to each term.51 + 0 =5151 + 1=5252 + 1=5353 + 2=5555 + 3=5858 + 5=6363 + 8=71
Question : Find the missing terms? 97,122,107,132,__,__.
A. 117,142B. 122,112C. 141,131D. 121,131
Answer : 117,142
Explanation:This series is a result of alternate +25 and -15.97 + 25=122122 – 15=107107 + 25=132132 – 15=117117 + 25=142
So, the next two terms are 117 and 142.
Question : Fill the missing term in the series
100, 92, 86 ,82, 74, 68, 64, 56, 50, __, ___.
A. 44, 36B. 40, 34C. 46, 38D. 44, 32
Answer : 46, 38
The number series are in successive subtraction series of – 8, -6, -4 and then again -8,-6,-4.So, the next terms after 50 will be 50-4=46 and 46-8=38.
Question : Select the missing number from the given responses.19, 35, 67, 131, 259, 515, ?
A. 1281B. 1291C. 1071D. 1027
Explanation :
11 × 2 – 3 = 1919 × 2 – 3 = 3535 × 2 – 3 = 6767 × 2 – 3 = 131131 × 2 – 3 = 259259 × 2 – 3 = 515515× 2 – 3 = 1027
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