The author of Business Mental Math, Valentin Nugmanov, has launched a free companion resource, the Business Mental Math Randomizer. This Excel-based practice tool can be downloaded here: casemaster.club/randomizer.
The Business Mental Math Randomizer is a cleverly designed collection of practice problems (set in business contexts) that can reset all of their values any time the user wishes. The result is a nearly infinite combination of word problems and values that students of mental math will want to keep handy.
For each topic (addition, division, fractional numbers, etc.) there are eight levels of problems, and the answers can be seen at the bottom of the sheet.
Then, with a push of a button, all the numbers change, and the student gets a whole new set of problems. Here is an example, before and after: