Solutions by everydaycalculation.com
This multiplication involving fractions can also be rephrased as "What is 21/60 of 40/90?"
2160 × 4090 is 745.
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/60×40/90 21/60×80/90 63/60×40/90
© everydaycalculation.com