small fixes

lib/math/validation.ts

@@ -1,6 +1,20 @@
 import { gcd } from "./fractions";
 import { simplifyRatio } from "./ratios";
 
+/** Parse a strict decimal string (digits and optional single dot). Rejects scientific notation, trailing letters, etc. */
+export function parseStrictDecimal(input: string): number | null {
+  const s = input.trim();
+  if (!/^\d+(\.\d+)?$/.test(s)) return null;
+  return parseFloat(s);
+}
+
+/** Parse a strict integer string (digits only, no dot or letters). */
+export function parseStrictInt(input: string): number | null {
+  const s = input.trim();
+  if (!/^\d+$/.test(s)) return null;
+  return parseInt(s, 10);
+}
+
 export type AnswerResult =
   | { correct: true; simplified: boolean }
   | { correct: false; message: string };