How Forex option Gamma can be more than 1

External question — Quantitative Finance Stack Exchange Author: user76029 Original post: https://quant.stackexchange.com/questions/80600 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. Problem statement: How forex option Gamma can be more than 1 (more than deal notional)? FX option details as below INRJPY FX Option deal (PUT Option and Sell DEAL) INR Notional=100 JPY Notional=161.29 Strike price 1.6129 Spot price 1.7092 Maturity 1 year volatility =10% interest rate INR =6.35% and interest rate JPY = -0.019% Greeks I am getting Delta =0.56 Gamma =-2.26 Requesting to clarify why Gamma is more than 1 and more than Notional? If more than 1 then How it is derived?