fastest way to calculate 1800/2.25

Question

I am ok with solving the problems but simple calculation such as 1800/2.25 slows me down by a lot. Do you have any fast and easy way to solve this division?

bhugi98 · Answer

1800/2.25=1800/(9/4)=1800*4/9=800

KarishmaB · Answer

Usually, converting decimals to fractions is advisable. Don't try to divide 1800 by 2.25. Convert 2.25 to fraction form: 2.25 = 225/100 = 9/4 (Note that both 225 and 100 are divisible by 25) It's good to know the multiplication tables as they help in quick calculations.

1800/(9/4) = 200*4 = 800

dabral · Answer

Another approach in case one does not want to turn 2.25 to 9/4. See the attached image.

Also, I wrote a blog post on how to deal with arithmetic manipulations on the GMAT:
https://www.gmatquantum.com/blog/how-to- ... tions.html

Cheers,
Dabral

Attachments

image23.png [ 18.15 KiB | Viewed 6069 times ]

JapinderKaur · Answer

I would second the suggestion of converting the decimal into fractions. But there's a quicker way of doing this conversion. 2.25 = 2+ 0.25 For the time-being, just consider the 0.25 bit. 0.25 =1/4. So, 2.25 = 2+ 1/4 = (8+1)/4 = 9/4 This is quicker than having to solve 225/100. I have given a few practice decimal-to-fraction conversions below. With some more practice, the fraction equivalents of decimals will hopefully start flashing in your mind automatically.

Practice Decimal-to-Fraction Conversions i) 3.75 ii) 4.67 iii) 9.125 iv) 7.33 v) 8.17 SOLUTIONS i) 0.75 = 3/4 So, 3.75 = 3+3/4 = 15/4 You don't need to go the 375/100 route. That will take longer. ii) 0.67 = 2/3 So, 4.67 = 4+ 2/3 = 14/3 iii) 0.125 = 1/8 (no need to learn this by rote. Just think: 0.125 is half of 0.250, and so, half of 1/4) So, 9.125 = 9+1/8 = 73/8 iv) 0.33 = 1/3 So, 7.33 = 7+ 1/3 = 22/3 v) 0.17 is close to 0.167, which is the half of 0.33. So, 0.167= 1/6. 8.17 = 8+1/6 = 49/6 I hope this helps.

rajatjain14 · Answer

It would be best if you can memorize these commonly used decimals for quicker calculations: 
   \frac{1}{2} = 0.5  
  \frac{1}{3}= 0.333  
  \frac{1}{4} = 0.25  
  \frac{1}{5} = 0.2  
  \frac{1}{6}= 0.1667  
  \frac{1}{7} = 0.1429  
  \frac{1}{8} = 0.125  
  \frac{1}{9} = 0.111  
  \frac{1}{10} = 0.1

Practice Problems: 
   4.67 = 4+2*\frac{1}{3}= \frac{14}{3}  
  2.25 = 2+\frac{1}{4} = \frac{9}{4}  
  6.125 = 6 +\frac{1}{8} = \frac{49}{8}  
  3.22 = 3 + 2*\frac{1}{9}= \frac{29}{9}

Regards,
Rajat

bumpbot · Answer

Automated notice from GMAT Club BumpBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

fastest way to calculate 1800/2.25

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards