# 1
| |||

| |||

Tricks to solve aptitude questions easily and quickly |

# 2
| |||

| |||

Re: Tricks to solve aptitude questions easily and quickly
As you want to get the details of tricks to solve aptitude questions easily and quicklyso here it is for you: Addition of numbers close to multiples of ten (e.g. 19, 29, 38, 59 etc.) This technique is useful for Mental calculations 116 + 39 (Here we can write this 39 as 40-1) = 116 + (40 - 1) = 116 + 40 - 1 = 156 - 1 (Instead of adding 39 to 116, we just add 40 to 116 (because we can do this without using pen and paper) and later we subtract one from it) = 155 Try this.. This is very useful tip while doing calculations. Now lets try another example. 116 + 97 = 116 + (100 - 3) = 116 + 100 - 3 (Here, instead of adding 97 to 116, we are just adding a 100 to 116 and then subtracting 3 from it Addition of decimals 12.5 + 6.25 = (12 + 0.5) + (6 + 0.25) = 12 + 6 + 0.5 + 0.25 (Here we just added the rounded numbers first and later we added the decimal numbers = 18 + 0.5 + 0.25 = 18.75 Subtractions Shortcuts : 250 - 96 = 250 - (100 - 4) (here, instead of subtracting 96 from 250, we are just subtracting 100 from 250 and then adding 4) = 250 - 100 + 4 (Why adding? because the actual amount we have to subtract from 250 is 96. but we are subtracting 100. That means, we are subtracting 4 numbers more than we actually deserve. so our 250 will feel bad. so we should add that 4 to it = 150 + 4 = 154 250 - 196 = 250 - (200 - 4) Lets see, 216 - 61 (Here i found it difficult to subtract 61 from 216) = 216 - (100 - 39) (So i just decided to subtract 100 to it and later will subtract the extra 39) = 216 - 100 + 39 (Hey, see here. How about writing this 39 as 40 -1 ?) = 116 + (40 - 1) (dont be confused. just practice this method and you will come to know how easy and efficient method it is = 156 - 1 = 155 Subtraction of decimals 47 - 9.9 (How about dividing this 9.9 as 9 + 0.9 ??) = 47 - (9 + 0.9) we can write this as... = 47 - 9 - 0.9 = 38 - 0.9 = 37.1 18.3 - 0.8 = 18 + 0.3 - 0.8 = (18 - 0.8) + 0.3 = 17.2 + 0.3 = 17.5 Shortcuts in Multiplications: Multiplication using multiples Assume that we should find out the result of 12X15. 12 x 15 (Here we can write this 15 as 5x3) = 12 x 5 x 3 (now 12x5 becomes 60) = 60 x 3 (For this you just calculate 3x6, that is 18 and add one Zero to it. that is 180) = 180 (see, how simple it is?) Multiplication by distribution Assume that we should find out the result of 12x17 12 x 17 (Here we can divide this 17 as 10+7. here, multiplying 12 with 17 is same as multiplying 12 with 10 and 7 separately and then adding the results) so, we can write it as = (12 x 10) + (12 x 7) Multiplication by "giving and taking" 12 x 47 (Here its little difficult for us to calculate the multiplication of 12 and 47 mentally. so just check for the ROUNDED number nearer to 47. Yes it is 50. so..... = 12 x (50 - 3) = (12 x 50) - (12 x 3) (we have discussed this rule earlier) = 600 - 36 = 564 Multiplication by 5 * If we have to multiply a number with 5, just divide the number with 2 and then multiply the result with 10. Confused? Its very simple step actually.... 428 x 5 (Now just divide the number with 2) = 428 x 1/2 = 214 (Now multiply it with 10. I mean just add a zero at the end :P) = 214 x 10 = 2140 (This is our result) Whats the logic behind this step? Very simple. * Lets say the number is X. * Now we are dividing the number with 2. so here X becomes X/2. * And then we are multiplying it with 10. So it will become 10x / 2 * Now cancel it with 2. so it becomes 10x / 2 = 5X = 5 multiplied by X. Thats it Multiplication by 10 ------------ just move the decimal point one place to the right 16 x 10 = 160 5.9 = 159 169.93 = 169.3 (Need an explnation for this too??? :P) Multiplication by 50 ------ divide with 2 and then multiply by 100 Well, this is also same process as we did for 5. Here we should add an extra zero. Thats it 18 x 50 = (18/2) = 9 = 9 x 100 = 900 Multiplication by 100 -------- move the decimal point two places to the right 45 x 100 = 4500 Multiplication by 500-------- divide with two and multiply with 1000 21 x 500 = 21/2 x 1000 = 10.5 x 1000 = 10500 Multiplication by 25 ---------- use the analogy Rs 1 = 4 x 25 Paise 25 x 14 (just divide the 14 as 10+4) = (25 x 10) + (25 x 4) = 250 + 100 ---> Rs2.50 + Rs1 = 350 Hey one more thing. Here you can use another technique too. Which we have used for multiplication with 5. Multiplication by 25 ----------- Divide by 4 and multiply by 100 36 x 25 = (36/4) x 100 = 9 x 100 = 900 Multiplication by 11 (if sum of digits is less than 10) 72 x 11 = 7+2 =9, it is Less than 10. so, = place this term 9 between 7 &2 Shortcuts in Division: There are so many types of divisions are there. Lets have a look. Division by parts --> Imagine you have Rs.874 . You have to give that to your two children. 874/2 [We can write this 874 as 800+74 (for our convenience) = 800/2 + 74/2 Division using the factors of the divisor: "this is also called as Double Division" 70/14 = (70/7)/2 (Because 7 and 2 are the factors of 14) = 10/2 = 5 Division using Fractions: 132/2 = (100/2 + 32/2) ( here we've broken the given fraction into two separate fractions) = (50 + 16) = 66 Division by 5 : Note: if you have to divide any number with 5, then divide it by 100 and then just multiply by 20 1400/5 = (1400/100) x 20 = 14 x 20 = 280 Division by 10 (Its very simple, just move the decimal point one place to the left) 0.5/10 = 0.05 Division by 50 ( Just divide with 100 then multiply by 2) 2100/50 = (2100/100) x 2 = 21 x 2 = 42 700/50 = (700/100) x 2 = 7 x 2 = 14 Division by 100 (just move the decimal point two places to the left) 25/100 = 0.25 Division by 500 (just divide with 100 and then multiply with 0.2) 17/500 = (17/100) x 0.2 = 0.17 x 0.2 = 0.034 Division by 25 (just divide by 100 and then multiply by 4 ) 500/25 = (500/100) x 4 = 5 x 4 = 20 750/25 = (750/100) x 4 = 7.5 x 2 x 2 = 30 |