My friend's son is 20 months old and recently she has had concerns about his speech development as he only has 4 words - mum, dad, dog and bab (meaning his sister.) He does understand what is said to him and can point out things when asked.
She had him assessed and as it turns out, he has the cognitive ability of a 3 year old. He is very quick with puzzles.
Is this unusual in a 20 month old? Could he be gifted in maths?