Math Tricks

Many of the people getting terrified on Mathematics.Here some cool tricks to solve math problems easily and enhance your speed when you calculate in your head.

 The 11 Times Trick

 1 . If we calculate 52 x 11, Take the original number and imagine space between both numbers,

 5____2   Now add  both numbers  (5+2=7) and  put it in that space. 5—(5+2)-2=572

 2 . If the numbers in the middle add up to a 2 digit number, just insert the second number and add 1 to the first: If we calculate 47 X 11, 4_____7 Now add both numbers (4+7=11) and put it in that space.

 (4+1)-(1)-7=517

 Quick Square If we square two numbers ending with 5, We can solve it easily using this trick. Mulitply

 the first digit by itself + 1, and put 25 on the end. Thats all!

 25 x 25                 2(2 + 1)—5 x 5                  2 x 3—25             625

 Multiply by        5

 This trick is super easy for solving complex questions.

 1 . Take any number, then divide it by 2 (in other words, halve the number). If the result is whole, add a 0 at the end. If it is not, ignore the remainder and add a 5 at the end.

 2682 x 5 = (2682 / 2) & 5 or 0 2682 / 2 = 1341 (whole number so add 0) 13410 Let’s try another:5887 x 5

 2943.5 (fractional number (ignore remainder, add 5) 29435

Few Tricks Which Will Help Solving Numerical Aptitude Question Quickly …

TRICK 1 :-  related to square of number 9

 (9)² = 81

 (99)² = 9801

 (999)² = 998001

 (99….n no.s of 9) to the power 2 =  (n-1)9’s followed by 8 then (n-1)0’s followed by 1

 so by the trick ::  (99999)² = 9999800001

TRICK 2 :- how to find square of any  no.

 (2)² = 4                      

 (11)² = 121

 (12)² = 144

 (123)² = 15129

 the trick is take the unit digit no. as ‘a’ and the remaining digits as ‘b’ and use the formula  b² 2ab a²

example :: 12² =  take a=2 and b=1     

 so start from right hand side

 a² =4

 2ab =4

 b²=1

 so putting in the sequence we have 144

 next for (123)² take a=3,b=12

 now , a²=9

 2ab = 72 (so we keep 2 and carry 7) =2

 b²=144 (+ carry 7 ) = 151

 so when we put in the sequence we get 15129

TRICK 3:- To calculate square of two digit numbers... From 26 to 50:-

 (if you remember the square of the no. from 1 to 25)

 trick:- square of x (x= 26 to 50) = (x-25)/ (50-x)square

 ex.- square of 46 = (46-25)/(50-46)square = 21/16= 2116 Ans.

 square of 42 = (42-25)/(50-42)square = 17/64= 1764

 square of 37 = (37-25)/(50-37)square = 12/ 169= 1369(take last two digits only, rest in reminder)

 square of 29 = (29-25)/ (50-29)square = 4/441 = 841

To Find Square Of A 3 Digit Number :

 LET THE NUMBER BE XYZ  SQ (XYZ) is calculated like this

 STEP 1. Last digit = last digit of SQ (Z)

 STEP 2. Second Last Digit = 2YZ + any carryover from STEP 1.

 STEP 3. Third Last Digit 2XZ+ Sq + any carryover from STEP 2.

 STEP 4. Fourth last digit is 2XY + any carryover from STEP 3.

 STEP 5 . In the beginning of result will be Sq(X) + any carryover from Step 4.

 EXAMPLE :  SQ (431)

 STEP 1. Last digit = last digit of SQ  (1) =1

 STEP 2. Second Last Digit = 231 +  any carryover from STEP  1.= 6

 STEP 3. Third Last Digit 241+ Sq  (3) + any carryover from STEP  2.= 241 +9= 17. so 7 and 1 carryover

 STEP 4. Fourth last digit is 243 + any carryover (which is 1) . = 24+1=25. So 5 and carry over 2.

 STEP 5 . In the beginning of result will be Sq(4) + any carryover from Step 4. So 16+2 =18.

 So the result will be 185761.

 If the option provided to you are such that the last two digits are different, then you need to carry out first two steps only , thus

 saving time. You may save up to 30 seconds on each calculations and if there are 4 such questions you save 2 minutes which may really affect UR Percentile score.

Shortcut Techniques For Percentage

 Shortcut 1:If we increased any value by x % and then decreased by y %. Then the resulting effect in percent will be:“+ x + y + xy /100”.

Various Examples related to this Percentage Short cuts are given below:

 Example 1:The price of goods is marks 20% more than the real price by the shopkeeper. After that the shopkeeper allowed a discount of 10%. Now What profit or loss did the shopkeeper will get?

 Solution:We solve this as follow by using the percentage shortcut1 as follow:

 The Loss (or) Profit he will get is = 20 – 10 + (+20)(-10)/100 =+ 8% (profit).

 Example 2:Side of the square is increased by 30%. Find the percentage increase in area.

 Solution:Here we again use the percentage shortcut 1.

 So the increased area percentage = 30 + 30 + (30)(30)/100 =69 % (increased).

 Example 3:Radius of the circle is decreased by 20%. What will be the percent change in area of the circle?

 Solution:Therefore by using thepercentage shortcut1:

 The Percent change in area of circle is= - 20 - 20 + (-20)(-20)/100 =-36% (decreased)

 Example 4:The price of a car is increased by 15% than after that again decreased by 15%. What will be the percent change?

 Solution:The percent change is = + 15 - 15 + (+15)(-15)/100 =- 2.25 % (decreased)

 Example 5:Length of a rectangle is increased by 40% and breadth of the rectangle is decreased by 40%. Find change in area.

 Solution:By using the formula of percentage shortcut given above:

 The percent change in area of rectangle is= 40 - 40 + (-40)(+40)/100 =-16 %( decreased)