# Alternative to tradertest.org for mental math practice

The most recommended resource for preparation for Optiver's math test is tradertest.org. But the website is down. What are the closest alternatives to it?

Although this question has been asked on this forum before the answers were unsatisfactory because one or the following things were missing from the suggested alternatives:

1. Floating point: Integer operations are generally easier and I need practice for operations on floating point numbers.

2. Penalty for error: On some sites you can just keep typing numbers till you get the right answer. In a real life scenario you will just move on to the next question without knowing that the last one was incorrect. I want to know how many did i answer incorrectly

3. 80 question in 8min format: This is not a necessity, but given the fact that optiver tests are genrally in this format it would be an added plus.

I basically want a site that is the closest simulator for Optiver's math test. So if there is any additional characteristics you know from your experience of giving the test kindly suggest a resource accordingly. If I have incorrectly assumed something about the test kindly correct me.

All this being said, I assume their test has a lot of variations accross countries or time, so I am only looking for the best estimate of what the test will be like.

Some websites that do not meet the above criteria are: rankyourbrain.com and arithmetic.zetamac.com

• This doesn't answer your question, but you may be able to salvage some of the material on tradertest.org using archive.org. Example: web.archive.org/web/20180101195426/http://tradertest.org:80 – user59 Aug 29 '18 at 16:00
• As an alternative you could change the zetamac code yourself, it seems simple enough. – Bob Jansen Aug 30 '18 at 19:13
• Hi Bob, you are talking about editing the javascript code available at their github right? Thats a good idea but I think if it comes to that it'll be easier for me to just code something similar in python. You've made me realise that I'm just being lazy :/ – Shreyans Aug 30 '18 at 22:15

http://tradermaths.com is probably the most similar to Optiver. The site has a Floating point option, penalty for error and 80 questions in 8 minutes.

I use https://graduatetrader.com/ they have 50 maths tests, each 8 mins long with 80 questions and negative marking. You can also make a profile to log your results.

You can try http://arithmetic.lemo.education/. Here you can actually train decimal calc, which was the hardest obstacle (at least for me).

Addition The trick here is to break up “ugly” numbers into round ones:

87 + 94 = (87 + 90) + 4 = 181

334 + 567 = (300 + 567) + 34 = 867 + 30 + 4 = 897 + 4 = 901


Subtraction Subtraction questions are similar, but you need to decide when to round up.

For example, if the second number’s second digit is bigger than the first number’s second digit, round up:

62 – 27 = 62 – 30 + 3 = 32 + 3 = 35

845 – 388 = 845 – 400 + 12 = 445 + 12 = 457


Multiplication Multiplying a 2- or 3-digit number by a 1-digit number is straightforward because you just separate them into smaller groupings:

47 x 5 = (40 x 5) + (7 x 5) = 200 + 35 = 235

397 x 4 = (300 x 4) + (90 x 4) + (7 x 4) = 1200 + 360 + 28 = 1588


For 2×2 multiplication, put the number with the larger second digit first and then group them into smaller units once again:

42 x 37 = 37 x 42 = (37 x 40) + (37 x 2) = (30 x 40) + (7 x 40) + (37 x 2) = 1200 + 280 + 74 = 1554


Division Division by 5. Multiply left number by 2 and divide by 10.

Squaring 2-Digit Numbers This formula is the trick for squaring 2-digit numbers:

X^2 = (X + Y) * (X – Y) + Y^2 And then you set Y such that either (X + Y) or (X – Y) ends with “0.” Examples:

49^2 = (49 + 1) * (49 – 1) + 1^2 = 50 * 48 + 1 = 2500 – (50 * 2) + 1 = 2401

56^2 = (56 + 4) * (56 – 4) + 4^2 = 60 * 52 + 16 = 60 * 50 + 60 * 2 + 16 = 3000 + 120 + 16 = 3136


Square Roots There are fewer “tricks” with square roots because no matter what you do, the answer will usually have decimal places.

But you can usually approximate the answer by thinking in terms of square numbers.

For example, let’s say they ask you the square root of 90:

You know that 9^2 = 81 and 10^2 = 100. And 90 is slightly closer to 81 than 100. So, you can say “slightly less than 9.5” (it’s ~9.49).

Check out tradinginterview.com, it helped me a lot