Very loosely, a number/vector/matrix/tensor can be considered to be objects where specifying the values of 0/1/2/3 indexes will give a number. (A mathematician

Very loosely, a number/vector/matrix/tensor can be considered to be objects where specifying the values of 0/1/2/3 indexes will give a number. (A mathematician might object to this on several grounds, such as that vectors/matrices/tensors are geometric objects which need not be expressed numerically as coordinates in any coordinate system)