Drishti
Quantitative Aptitude for IPMAT , NPAT , SET : Online and Offline Resources you should refer!
For curating this post , I asked some of my batchmates at IIM Rohtak about their mode of preparation , the resources they referred etc. and I realized that the mode of preparation for competitive exams like IPMAT , NPAT , SET varies from student to student and to devise a strategy that works best for you, you firstly need to understand your strong and weak points.
Some people prefer joining coaching institutes and devoting an hour or so daily on their IPMAT prep, others might join a crash course and complete that preparation in 2 months. Interestingly, the results can be more or less equal.
However, even if you choose not to join a coaching institute , there are a ton of free resources available online and some of these free resources are even better than the paid ones.

For Quants , focus on the 8 main arithmetic topics , understand their key concepts and attempt a few questions till you feel confident about them.
Books you should refer for Quants
If you consider your Quants to be "strong" - Gautam Puri for Quantitative Aptitude
If you consider your Quants to be "weak" - RS Aggarwal for Quantitative Aptitude (Alternatively, you can use SSC books that provide you with basics of each topic and questions BUT I personally recommend using RS Aggarwal )
If you have enrolled yourself in a coaching institute , do NOT take their modules for granted. Some coaching institutes ( I would prefer not to take any names here ) have really good modules and study material and if you have access to those modules , start practicing them first instead of buying new books.

Here are some topic wise free resources ( for IPMAT Rohtak , NPAT and other equivalent exams)
CI & SI, Profit and loss - Link
Time, Speed , Distance - Link
Arithmetic Tricks - Links
Percentages - Link
You will find a ton of YouTube channels providing free content on all the arithmetic topics, select the channel you like and go ahead , a few of them have been linked in my other post "How to prepare for IPMAT Rohtak and other BBA entrances"
I recommend attempting 3-5 mocks at least before writing the final IPMAT exam , these mocks are provided by coaching institutes on their portals or can be purchased at affordable prices.
A lot of students find the sectional tests provided by the coaching institutes on their apps/portals to be useful, one should depend on these tests for increasing speed and if you have ample of time , do attempt these.
Other topics you MUST cover - Permutations and Combinations, Mixtures , Probability , Time, Speed and Distance.
Apps like Unacademy provide many free videos and live classes and some of them are really beneficial. You can try that out too!
There is no dearth of resources online if you REALLY wish to crack IPMAT / NPAT or any other entrance exam. All the best for your prep!
For any genuine queries , you can drop me an email - drishti.bibliophile@gmail.com
Also Read - My IPM IIM-R interview experience