How to round up large Number in appian

There's probably a more efficient way to do this, but here's at least an example that would work. I think you have to get your result into a state where it can easily be rounded, so I used a combination of log() and power():

a!localVariables(
  /* Original Variables */
  local!interest: 10,
  local!months: 12,
  
  /* Original Expression */
  local!base: 1+ local!interest,
  local!power: power(local!base, local!months),
  
  /* New Logic */
  local!numberOfDigits:floor(log(local!power, 10)),
  local!decimalOnly: local!power / power(10, local!numberOfDigits),
  local!rounded: round(local!decimalOnly, 2),
  
  /* Final Result */
  local!rounded * power(10, local!numberOfDigits)
)

There's probably a more efficient way to do this, but here's at least an example that would work. I think you have to get your result into a state where it can easily be rounded, so I used a combination of log() and power():

a!localVariables(
  /* Original Variables */
  local!interest: 10,
  local!months: 12,
  
  /* Original Expression */
  local!base: 1+ local!interest,
  local!power: power(local!base, local!months),
  
  /* New Logic */
  local!numberOfDigits:floor(log(local!power, 10)),
  local!decimalOnly: local!power / power(10, local!numberOfDigits),
  local!rounded: round(local!decimalOnly, 2),
  
  /* Final Result */
  local!rounded * power(10, local!numberOfDigits)
)