Bubble uses JavaScript's native number type, which can only accurately represent integers up to 15 significant digits. Any integer larger than 9,007,199,254,740,991 will be rounded to a nearby value. This is a fundamental limitation of how JavaScript handles large numbers, not specific to Bubble.
What you might notice
A number with more than 15 digits is stored as a slightly different value than what you entered
For example, 159312620657051572 becomes 159312620657051600
Very small decimal numbers with many significant digits may also be affected
Workaround
Store large numeric values in text fields instead of number fields. This preserves the exact value without any rounding. There may also be community-built plugins available that handle large number math operations with arbitrary precision.
This is a limitation of JavaScript's native number representation. You can read more here.