.  00.0000/journal.pone.0000000.t000  ###### Hierarchical linear regression predicting conceptual understanding (Model 0a) and overall mathematics achievement (Model 0b) by quantitative and domain-general skills.  ![](pone.0000000.t000){#pone.0000000.t000g}    -------------------------------------------------------------------------------------------------------------------------------------------                                                Model 0a\                      Model 0b\                                                                                             DV: conceptual understanding   DV: mathematics achievement                              --- ---------------------------------------- ------------------------------ ----------------------------- ------ ------- -------- ---------   0   Age (months)                             .000                           0.000                         .000   .000    0.000    .000    0   Age (months)                             .000                           0.000                         .000   .000    0.000    .000        Working memory (composite)               .000                           0.000                         .000   .000    0.000    