LGS 2026: Mental Ability Shortcuts — 20 Solved Examples

Mental ability shortcuts for the LGS exam on April 26, 2026. Expect 5-10 questions from reasoning and simple maths. All examples are at easy/SSLC level.

Pattern 1: Number Series

How to solve: Find the difference between consecutive numbers. If differences are constant, it is an arithmetic series. If differences are increasing, check if they follow a pattern (like +2, +4, +6 or squares/cubes).

Example 1

Series: 2, 5, 8, 11, ?

Position	Number	Difference
1st	2	—
2nd	5	+3
3rd	8	+3
4th	11	+3
5th	14	+3

Answer: 14 (constant difference of 3)

Example 2

Series: 1, 4, 9, 16, ?

Position	Number	Pattern
1st	1	1 x 1
2nd	4	2 x 2
3rd	9	3 x 3
4th	16	4 x 4
5th	25	5 x 5

Answer: 25 (perfect squares)

Example 3

Series: 2, 6, 18, 54, ?

Position	Number	Pattern
1st	2	—
2nd	6	x 3
3rd	18	x 3
4th	54	x 3
5th	162	x 3

Answer: 162 (each number multiplied by 3)

Example 4

Series: 1, 2, 4, 7, 11, ?

Position	Number	Difference
1st	1	—
2nd	2	+1
3rd	4	+2
4th	7	+3
5th	11	+4
6th	16	+5

Answer: 16 (differences increase by 1)

Pattern 2: Odd One Out

How to solve: Find what is common among 4 items. The one that does not fit is the answer.

Example 5

Find the odd one: Apple, Mango, Carrot, Banana, Orange

Item	Category
Apple	Fruit
Mango	Fruit
Carrot	Vegetable
Banana	Fruit
Orange	Fruit

Answer: Carrot (all others are fruits)

Example 6

Find the odd one: 2, 5, 7, 11, 15

Number	Prime?
2	Yes
5	Yes
7	Yes
11	Yes
15	No (3 x 5)

Answer: 15 (all others are prime numbers)

Example 7

Find the odd one: January, March, June, July, August

Month	Days
January	31
March	31
June	30
July	31
August	31

Answer: June (all others have 31 days)

Pattern 3: Analogy (A : B :: C : ?)

How to solve: Find the relationship between A and B, then apply the same relationship to C.

Example 8

Doctor : Hospital :: Teacher : ?

Pair	Relationship
Doctor : Hospital	Person : Workplace
Teacher : ?	Person : School

Answer: School

Example 9

Pen : Writer :: Brush : ?

Pair	Relationship
Pen : Writer	Tool : User
Brush : ?	Tool : Painter

Answer: Painter

Example 10

Calf : Cow :: Puppy : ?

Pair	Relationship
Calf : Cow	Young : Adult
Puppy : ?	Young : Dog

Answer: Dog

Example 11

3 : 27 :: 5 : ?

Pair	Relationship
3 : 27	Number : Cube (3^3 = 27)
5 : ?	Number : Cube (5^3 = 125)

Answer: 125

Pattern 4: Direction Problems

Key compass points to remember:

Direction	Position
North	Up
South	Down
East	Right
West	Left
North-East	Up-Right
North-West	Up-Left
South-East	Down-Right
South-West	Down-Left

Shortcut: Draw a small compass on your question paper. Trace the path step by step.

Example 12

A man walks 5 km North, then turns right and walks 3 km. Which direction is he facing?

Step	Direction	Facing
Start	—	North
Walk 5 km	North	North
Turn right	—	East
Walk 3 km	East	East

Answer: East

Example 13

A person walks 10 m South, turns left and walks 5 m, then turns left and walks 10 m. How far is he from the starting point?

Step	Direction	Movement
1	South	10 m
2	Turn left = East	5 m
3	Turn left = North	10 m

He went 10 m South then 10 m North (cancels out). Net displacement = 5 m East.

Answer: 5 m

Example 14

If you face North and turn 90 degrees clockwise, which direction do you face?

Clockwise from North: North - East - South - West. One 90-degree turn = East.

Answer: East

Pattern 5: Percentage Shortcuts

Percentage	Shortcut
10% of any number	Divide by 10
20% of any number	Divide by 5
25% of any number	Divide by 4
50% of any number	Divide by 2
1% of any number	Divide by 100
5% of any number	Half of 10%
15% of any number	10% + 5%
33.33%	Divide by 3

Example 15

Find 15% of 200.

Step	Calculation
10% of 200	200 / 10 = 20
5% of 200	20 / 2 = 10
15% = 10% + 5%	20 + 10 = 30

Answer: 30

Example 16

A book costs Rs. 400. After a 25% discount, what is the price?

Step	Calculation
25% of 400	400 / 4 = 100
Price after discount	400 - 100 = 300

Answer: Rs. 300

Pattern 6: Profit and Loss

Term	Formula
Profit	Selling Price - Cost Price
Loss	Cost Price - Selling Price
Profit %	(Profit / Cost Price) x 100
Loss %	(Loss / Cost Price) x 100
Selling Price (with profit)	CP x (100 + Profit%) / 100
Selling Price (with loss)	CP x (100 - Loss%) / 100

Example 17

A shopkeeper buys an item for Rs. 500 and sells it for Rs. 600. What is the profit percentage?

Step	Calculation
Cost Price (CP)	Rs. 500
Selling Price (SP)	Rs. 600
Profit	600 - 500 = Rs. 100
Profit %	(100 / 500) x 100 = 20%

Answer: 20%

Example 18

An article is bought for Rs. 800 and sold at 10% loss. What is the selling price?

Step	Calculation
CP	Rs. 800
Loss	10% of 800 = 80
SP	800 - 80 = Rs. 720

Answer: Rs. 720

Pattern 7: Simple Interest

Formula	SI = (P x R x T) / 100
P	Principal (original amount)
R	Rate of interest per year
T	Time in years
Total Amount	P + SI

Example 19

Find the simple interest on Rs. 10,000 at 5% per year for 2 years.

Step	Calculation
P	Rs. 10,000
R	5%
T	2 years
SI	(10000 x 5 x 2) / 100 = Rs. 1,000

Answer: Rs. 1,000

Pattern 8: Average

Formula	Average = Sum of all items / Number of items

Example 20

The marks of 5 students are 60, 70, 80, 90, and 50. Find the average.

Step	Calculation
Sum	60 + 70 + 80 + 90 + 50 = 350
Number of students	5
Average	350 / 5 = 70

Answer: 70

Quick Reference: Multiplication Tables to Memorise

x	12	13	14	15	16	17	18	19
2	24	26	28	30	32	34	36	38
3	36	39	42	45	48	51	54	57
4	48	52	56	60	64	68	72	76
5	60	65	70	75	80	85	90	95
9	108	117	126	135	144	153	162	171

Squares to Remember

Number	Square
11	121
12	144
13	169
14	196
15	225
16	256
17	289
18	324
19	361
20	400
25	625
30	900

Cubes to Remember

Number	Cube
2	8
3	27
4	64
5	125
6	216
7	343
8	512
9	729
10	1000

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Tip: LGS mental ability questions are straightforward. Number series and odd-one-out appear almost every year. Practice the patterns above and you can solve them in under 30 seconds each.