Display 2 decimals when simplifying

[YannickNeyt]

I'm making a question about money, and I'd like simplified numbers to be displayed with exactly 2 decimals, as most prices are.

Something like: $\simplify[decimals=2]{{p1}+{p2}}$ outputting $2.20$ if p1=1.05 and p2=1.15 would be nice.

[christianp]

That's a good suggestion, thanks.

For now, you could use the dpformat or currency functions? You won't get simplification rules applied, so you'll need to beware of things like adding negative numbers.

[YannickNeyt]

Thanks, that seems to work fine in most cases, except when the amount is less than 1. Something like {currency(a,'','')} or $\var{latex(currency(a,'',''))}$ for a=0.80 outputs 80 or $80$ instead.

[christianp]

The currency function prefers to render numbers less than 1 using the 'cents' symbol, which is the third argument. For example, currency(0.8,'£','p') would produce 80p. I think dpformat does what you want.

I do want to implement the [decimals=2] option you suggested, so I'm leaving this open.

[YannickNeyt]

I missed your mention of dpformat... I made a custom function based on currency: (the number n is the only input)

var s = Numbas.math.niceNumber(100*n,{precisionType:'dp',precision:0}); if(n >=0.995){ if(n%1 < 0.005) { return Numbas.math.niceNumber(Math.floor(n)); } else if(n%1 >= 0.995) { return Numbas.math.niceNumber(Math.ceil(n)); } s = s.replace(/(..)$/,'.$1'); // put a dot before the last two digits, representing the cents return s } else { s = s.replace(/(..)$/,'0.$1'); // put 0. before the last two digits, representing the cents return s
}