# Handling of large numbers and mod( )-function in CAS vs. Algebra-window

For reference see: https://www.geogebra.org/m/y9m8w9u9

When I define a variable as a very large number e.g. a:=3900000002578039102900 in the CAS window it is simultaneously displayed in the algebra window as "a=3900000002578039000000" (when using GeoGebra 5 classic) or even more confusig as "a=3900000002578038915100" (when using GeoGebra Classic in a browser), which is a bit confusing.

If I try to calculate e.g. mod(a,97) I get a "not defined" error in the algebra window.

Entering the same expression in the CAS-window leads to the correct answer 64.

To make matters worse: When I enter the exact same number as above but via the input bar/algebra window, it automatically gets converted to 3900000002578039000000 (desktop app 5.0) or 3900000002578038915100 (web, 6.0) and if I try to calculate mod(a,97) via the CAS view I get the (incorrect) answer 81.

I assume that mod(a,b) is calculated differently wheter entered in CAS or algebra-window? But why is the number "rounded" when I enter it via the input bar/algebra window in the first place? Is there an upper boud to how large numbers can be handled in algebra vs. CAS and does it differ between the two?

The Algebra View works to 15 significant figures only

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