And when one looks in the Tanakh itself at the frequency and usage of the two words - echad and yachid - it is very quickly and easily seen that echad, not yachid, is in fact the standard Hebrew word for a simple one. Echad is used over 900 times in the Hebrew Bible, making it the most frequently used adjective in the Tanakh. Here are some examples of its usage where the word "one" is translated from echad: "one place" (Gen. 1:9); "one man" (Gen. 42:13); "one law" (Ex. 12:49); "one side" (Ex. 25:12); "one ewe lamb" (Lev. 14:10); "one of his brethren" (Lev. 25:48); "one rod" (Num. 17:3); "one soul" (Num. 31:28); "one of these cities" (Deut. 4:42); "one way" (Deut. 28:7); "one ephah" (1 Sam. 1:24); "one went out into the field" (11 Kings 4:39); "one shepherd" (Ezek. 37:24); "one basket" (Jer. 24:2); "one [thing]" (Ps. 27:4); "Two are better than one" (Ecc. 4:9); "one day or two" (Ezra 10:13).
Sometimes it is simply part of a number, like "eleven" (echad + 'asar, one plus ten), in , for example Genesis 32:22. Sometimes it is as well translated by an indefinite article (a[n]): "a new cart" (1 Sam. 6:7); "a juniper tree" (1 Kings 19:4,5); "a book" (Jer. 51:60).
Perhaps most importantly, echad clearly has the meaning of single, alone, ONLY one, or JUST one, the ideal of a limit of one (Num. 10:4; Josh. 17:14; Esth. 4:11; Isa. 51:2). In Deuteronomy 17:6, for example, it really isn't precise English to translate echad merely as "one". For if the "one" witness referred to is the second of the third witness, then that one witness is enough to convict the hypothetical person of murder. The meaning is that a person must not be put to death of the evidence of only one witness (which is the way the NRSV translates it). Echad means "one" and ONLY one.